福建省几种主要红壤性水稻土的硝化与反硝化活性

Nitrification and Denitrification Potential in Different Types of Paddy Soils in Fujian Province

在实验室培养条件下,研究了4种红壤性水稻土硝化和反硝化活性的差异。结果表明,氮肥在4种土壤中的硝化率差异极显著,表现为灰泥土>浅灰黄泥沙土>灰黄泥土>黄泥土,培养642h后硝化率分别为85.6%、24.3%、22.5%和6.7%。不同土壤的硝化率与土壤中硝化细菌数(主要是亚硝酸菌)显著相关(r2=0.95),pH值最高和最低的土壤其硝化率分别表现出最高和最低,但浅灰黄泥沙土在pH5.1条件下,硝化率可达24.3%。在施氮肥条件下,不同土壤的反硝化活性差异也极显著,其中黄泥土反硝化活性最高,氮肥反硝化损失量达25.16μgN·g-1土,占施氮量的12.12%,反硝化作用可能是该土壤氮肥损失的主要途径之一;另外3种土壤间反硝化活性差异不显著,氮肥反硝化损失量仅占施氮量的-0.15%～0.27%。反硝化菌数量与氮肥反硝化损失量之间无明显相关性。可以认为反硝化作用在不同类型土壤氮肥损失中的作用和贡献有很大差异。

In this paper a soil incubation experiment is conducted under laboratory condition to reveal differences of nitrification and denitrification potential in four types of acidic paddy soils. The results showed that nitrification rates of nitrogen fertilizer ((NH4)2 SO4) in four soils appeared significant difference (P<0.01), with an order of gray soil>light gray- yellow sandy soil>gray- yellow soil>yellow soil, and the rates raised by 85.6% , 24.3% , 22.5% and 6.7% , respectively, after 642 h incubation. There was a significant relationship between nitrification rate and nitrifying bacteria population, and the higher the soil pH, the higher the nitrification rate in the soils, but nitrification rate in light gray- yellow sandy soil reached to 24.3% at pH 5.1. Denitrification potential also showed significant differences (P<0.01) among these soils, and the highest denitrification potential appeared in yellow soil, resulting in nitrogen loss amount of 25.16 μ gN· g- 1 soil which accounted for 12.12% of nitrogen fertilizer applied (KNO3). Denitrification may be one of main loss ways of nitrogen fertilizer in this soil. But there were no significant differences of denitrification among the other soils, in which nitrogen loss was only - 0.15% ～ 0.27% of nitrogen fertilizer applied. There was no correlation between denitrifying bacteria and nitrogen loss amount. It may be deemed that the contribution of denitrification to nitrogen loss was great different among these soils studied.